1. Field of the Invention
This invention relates to additives for hydrocarbons having utility to impart to lubricating oils when incorporated therein, one or more of the properties of improved viscosity index, lowered pour point, sludge dispersancy, increased load carrying ability, increased rust inhibition and increased resistance to oxidation; and, to residual fuels and heavy distillates an improvement in cold flow properties. More particularly, this invention relates to such additives for hydrocarbons which comprise the copolymers of an ethylenically unsaturated polar monomer and sulfur dioxide, which copolymers may contain one or more additional monomers including substantially linear alpha olefins, cyclic olefins and conjugated diolefins.
2. Prior Art
The products resulting from the polymerization of sulfur dioxide with unsaturated compounds such as unsaturated alcohols, ethers, esters and acids (see U.S. Pat. No. 2,144,292); and, with olefins and ethylenically unsaturated polar compounds (see U.S. Pat. Nos. 2,241,900, 2,645,631, 3,563,961 and 3,684,778) are well known in the art. The copolymers of sulfur dioxide and unsaturated compounds are prepared by various processes, including bulk, solution and emulsion polymerization.
In U.S. Pat. Nos. 3,409,548 3,396,115 and British Pat. No. 1,258,758 copolymers of olefins and sulfur dioxide are taught as useful in oil-based fracturing fluids, dry cleaning solvents and coking, respectively.
U.S. Pat. No. 2,652,368 describes the use of alkylene sulfone copolymers of SO.sub.2 and olefins in lubricating oil compositions to enhance viscosity temperature performance in torque converters. These copolymers were obtained by the polymerization of alpha-olefinic hydrocarbons having from 7 to 24 carbon atoms and SO.sub.2 at the latter's reflux temperature and in the presence of catalyst such as peroxides and nitrates.
U.S. Pat. No. 3,442,790 shows C.sub.12 -C.sub.52 olefins and sulfur dioxide copolymers as wax crystal modifiers. These materials are added to wax-containing petroleum oil materials, for example, so as to modify the size and shape of wax crystals in such a manner as to permit more rapid separation of the wax during the dewaxing of the hydrocarbon oil.